Qualitative analysis of activity data, emission factors and grid maps

Obviously, any projection of future environmental conditions rests critically on the underlying emission factors and their relationship with relevant human activities or drivers. The IMAGE model has incorporated the most recent and authoritative sources. Despite ongoing efforts to collect data and enhance statistical procedures and modelling, many emission sources of greenhouse gases and other anthropogenic trace gases remain uncertain. Van Aardenne et al. (2001) have overviewed the qualitative analysis of activity data, emission factors and grid maps as in IMAGE. As a rule, emissions from large point sources like power plants tend to be of acceptable quality, while smaller and dispersed sources are typically poor to very poor. Whereas global or large-scale regional aggregate budgets are generally reasonably well known, the contribution of sectors and activities by geographic location is for the most part much more uncertain. Emission factors that depend on fuel properties, like CO₂ and sulphur dioxide (SO₂), can be estimated within narrow ranges, but others are very sensitive to technological details, local conditions like soil properties, and management practices. This induces not only uncertainties in the initial inventories, but also in future emission projections.

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